MODULE B: BASIC CHEMISTRY
LESSON 3B: Nomenclature & Oxidation-Reduction Reactions

I.Definition of Terms

A.OXIDATION: The loss of electrons during a chemical reaction.

B.REDUCTION: The gain of electrons during a chemical reaction.

C.OXIDATION - REDUCTION REACTION: A reaction in which electrons are shifted from a donor atom (electron donor) to an acceptor atom or molecule (electron acceptor); also called a re-dox reaction.

D.OXIDIZING AGENT: The substance in an oxidation/reduction reaction that accepts the shifted electrons.

E.REDUCING AGENT: The substance in an oxidation/reduction reaction that donates the shifted electrons.

II.Nomenclature

A.Definition: A system of words used to name things in a particular discipline.

1.The name of a compound has to include enough information to tell chemists the composition and structure of the compound.

2.Can be used to name ions (including simple ions and polyatomic ions) as well as ionic and molecular compounds.

B.Nomenclature steps for Simple Ions

1.Metal Cations with only one form (representative)

a.Identify the metal.

b.Add “ion”.

c.Example: K+ = Potassium ion.

2.Metal Cations with more than one form (transition)

a.Identify the metal.

b.Give the charge on the ion a roman numeral in parentheses.

c.Add “ion”.

d.Example: Cr+2 = Chromium (II) ion.

3.Anions (representative)

a.Replace the ending of the element with “ide”.

b.Add “ion”.

c.Example: Cl- = Chloride ion.

C.Nomenclature steps for Polyatomic Ions

1.These include the following:

a.Ions with more than one atom.

b.Ions that contain oxygen as a constituent.

c.Ions that are commonly anions.

d.The names must be memorized.

i.NO2-: nitrite ion.

ii.NO3-: nitrate ion.

iii.NH4+: ammonium ion.

iv.PO4-3: phosphate ion.

v.HPO4 -2: hydrogen phosphate ion.

vi.H2PO -4: dihydrogen phosphate ion.

vii.CO3-2: carbonate ion.

viii.HCO3-: bicarbonate ion (hydrogen carbonate).

ix.SO3 -2: sulfite ion.

x.SO4-2: sulfate ion.

xi.HSO4-:bisulfate ion (hydrogen sulfate).

xii.OH-: hydroxide ion.

xiii.CH3CO2-: acetate ion.

xiv.Cr2O7-2: dichromate ion.

xv.CN-: cyanide ion.

xvi.OCl-: hypochlorite ion.

xvii.MnO4-: permanganate ion.

2.Steps for naming a Polyatomic Ions in compounds (one element or ion and a polyatomic ion):

a.Use the name of the ion.

b.Add the name of the polyatomic ion.

c.Example: MgSO4 (magnesium sulfate)

3.Two rules for naming compounds composed of polyatomic ions:

a.Rule One: The more positive portion of the compound is named first.

i.This includes:

  • Metal
  • Positive polyatomic ion
  • Hydrogen
  • Least negative non-metal (farthest left)

b.Rule Two: The more negative portion is named and written last.

c.Example: NaNO3

i.Sodium + Nitrate ion = Sodium Nitrate

D.Nomenclature for Ionic Compounds

1.Steps for naming Ionic Compounds that include one metal and one non-metal bonding together.

a.Name the positive (cation) ion.

b.Name the stem of the negative (anion) ion.

c.Add ide.

d.Example: NaCl

i.Na+ and Cl-

ii.Sodium + Chlor + ide

iii.Sodium chloride

e.The following stems are commonly used:

i.Ox: oxygen

ii.Chlor: chlorine

iii.Brom: bromine

iv.Iod: iodine

v.Nitr: nitrogen

E.Nomenclature for Molecular compounds

1.Steps for naming Molecular Compounds that include one non-metal and another non-metal bonding together.

a.Use the prefix of the first element.

b.Add element name.

c.Use the prefix of the second element.

d.Use the stem of the second element.

e.Add ide.

f.Example: P2O3

i.Di+phosphate+tri+ox+ide

ii.Diphosphate trioxide

g.The following prefixes are frequently used:

i.Mono: one

ii.Di: two

iii.Tri: three

iv.Tetra: four

v.Penta: five

vi.Hexa: six

vii.Hepta: seven

viii.Octa: eight

ix.Note: Mono means one and is only used before the second element. If no prefix appears before the first element, assume one.

x.If two vowels appear together, drop the vowel from the prefix

III.Chemical Reactions

A.Definitions:

1.Chemical Reaction: Two substances colliding with enough energy to overcome the repulsion of electrons (i.e. electron movement).

2.Chemical equation: Shorthand method of describing a chemical change using symbols, arrows and formulas

3.Activation energy – Something that can increase molecular collisions and change the rate of the chemical reaction.

a.Examples:

i.Heat

ii.Increased concentrations of substances

iii.Pressure

iv.Catalyst

4.Catalyst – Substance that speeds a reaction without being chemically changed in the process (carbonic anhydrase)

5.Balance – Atoms on one side of an arrow must equal the atoms on the other side of the arrow.

6.Law of Conservation – Matter cannot be created or destroyed – only changed.

7.Reactants – substances entering into a reaction.

8.Products – Substances formed by the reaction.

9.Conditions – circumstances that may need to be present for the reaction to take place

B.Speed of chemical reactions

1.Slow

a.Examples: Decay, Rust

2.Moderate

a.Examples: Cement setting

3.Fast

a.Explosion of dynamite, coal burning

C.Types of chemical reactions

1.Synthesis (Combination): A + B - AB

a.Combination of 2 or more substances (reactants) to form different, more complex substances (products).

b.Substances formed are usually compounds or or polyatomic ions.

c.Bonds are formed in these reactions.

d.Energy is required for this reaction to occur.

e.Example

i.Reactions involving oxygen are often called combustion reactions.
C + O2 CO2
“heat”

ii.Oxidation-Reduction Reaction

  • Oxidation – Loss of electrons during a chemical reaction.
  • Reduction – Gain of electrons during a chemical reaction.
  • Memory-Aid Acronym: OIL RIG

OIL – Oxidation Is Loss

RIG – Reduction Is Gain

  • Oxidizing agent – Accepts the electrons (anion) and is being reduced.
  • Reducing agent – Releases the electrons (cation) and is being oxidized.
  • Simple electrolyte cell

Cathode (-) attracts cations (+), oxidation takes place and electrons are released.

Anode (+) attracts anions (-), reduction takes place where electrons are accepted.

Causes flow of electrons and electrical current.

  • Examples

Batteries

Oxygen analyzers

Blood gas electrodes

2.Decomposition (Breakdown): AB -- A + B

a.One complex substance (a compound) undergoes a reaction to form two or more new (simpler) substances (elements or compounds).

b.During this reaction, chemical bonds are broken and heat (as energy) is released.

c.Example:

i.Breakdown of complex nutrients in a cell to release energy for other cellular functions.

  • Carbohydrates
  • Proteins
  • Fats

d.Products of these reactions are essentially “waste products”.

e.It is common for the energy released during a decomposition reaction to be used to drive a synthesis reaction.

3.Exchange (Replace): AB + CD - AD + CB

a.Breakdown of substances (reactants) to form different substances (products).

b.Bonds are both decomposed and synthesized in these reactions.

c.Energy is required and released in this reaction.

d.Example

i.H.Lactic + NaHCO3 Na.Lactate + H2CO3

e.Types of Exchange Reactions

i.Single-replacement Exchange

  • An element and a compound react where the first element replaces an element in the compound.
  • Example:

Zn + CuSO4 ZnSO4 + Cu

ii.Double-replacement Exchange

  • Two compounds exchange ions.
  • Example:

AgNO3 + HCl  HNO3 + AgCl

iii.Neutralization

  • An acid reacts with a base , generally producing a salt, water (or weak acid) and heat.
  • Example

HCl + NaOH NaCl + H2O

(strong acid) (base) (salt) (water)